Olefin/maleic acid copolymers have been shown effective as agents for controlling blood cholesterol levels as described in Fields and Johnsons U.S. Pat. No. 3,923,972 issued Dec. 2, 1975. Olefin/maleic copolymers can be prepared in the anhydride form by the polymerization methods described in the aforesaid patent or in the patents there cited, for example, Fields and Johnson U.S. Pat. No. 3,340,680. Such polymerization methods frequently utilize a solvent for the reaction which dissolves the monomers, but not the resulting copolymer, so that the copolymer precipitates. This is an effective method of preparing and isolating polymer for normal industrial uses, although with higher olefins it may be difficult to obtain the polymer in readily filterable form. However polymer obtained in such procedures generally contains substantial amounts of residual monomers and low molecular weight polymer materials. A Hazen and Heilman U.S. Pat. No. 3,560,456 describes a method in which a copolymer of maleic anhydride and an olefin of 16 to 18 carbon atoms is precipitated from solution by propyl alcohol in order to have the polymer in particular form for filtration. The procedure is useful but the product still contains substantial amounts of low molecular weight materials and some residual amounts of esterified polymer. The product obtained by the described procedure can, if desired, be utilized for further refinement in accord with the present invention.